Directions:

Place 4 cups of water in a medium saucepan. Add the slices of ginger, 2 tablespoons of the rice vinegar, and the salt. Bring to a boil, then simmer vigorously (just below a rolling boil) for 20 minutes.

While the ginger is simmering, prepare the shrimp: peel them, leaving the tail intact. Make a deep cut to devein them, then spread them open in butterfly fashion, keeping them attached at the tail. Salt them lightly.

Prepare the dressing: Place 6 tablespoons of the rice vinegar in a small bowl with the vegetable oil, soy sauce, and dark sesame oil. Whisk vigorously until a smooth dressing is formed, then season to taste with salt.

When the ginger water has simmered for 20 minutes, turn off the heat. Let it cool for a few minutes. Then add the shrimp to the water, and let them sit until just cooked, about 1 to 2 minutes. Remove the shrimp. If they've curled up, uncurl them with your fingers. Toss them in a small bowl with 2 tablespoons of the dressing. Reserve.

Remove the ginger slices from the water still in the pan and discard. Add the rice to the water, bring to a boil, and boil, uncovered, until the rice is just cooked, about 15 minutes (you may need to add a little additional water toward the end). Remove the rice, and toss with the remaining teaspoon of rice vinegar and the sugar.

Toast the sesame seeds in a 500 degrees oven until golden brown, about 5 minutes, and toss with the rice. Reserve.

Wash and dry the salad greens. Toss together the soft greens, watercress leaves, and alfalfa sprouts in a large bowl. Add about two thirds of the remaining dressing, and blend well.

Divide the salad among 4 dinner plates. On each plate, place 4 slices of avocado on top of the greens in pinwheel fashion, with the tips of the avocado slices at the center of each plate. Position 4 shrimp on each plate, cut side up, tails toward the center of the plates, nestled between avocado slices. Divide the rice among the 16 shrimp, patting a bit along the length of each butterflied shrimp. Drizzle the remaining dressing over the avocado slices and the shrimp.

Hold the sheets of nori about 3 inches from an open flame. Toast on both sides until they crisp, about 30 seconds. Cut into thin shreds, and garnish the shrimp with the shreds.